In praise of Hawk-Eye, the tennis dispute settler

Remember Cyclops - the one-eyed monster that used to sit, squat and unblinking, on the service line at Wimbledon and bleep? Ilie Nastase once got down on his hands and knees during a dramatic centre court encounter and tried to have a conversation with Cyclops. He was somewhat miffed when he got no response.

John McEnroe, realising that eliciting a response might be pushing it, turned to the umpire during another desperate duel that was not going his way and said, "You know, I'm sure that thing knows who I am!"

Now, dear Cyclops has been carted away to computer heaven and in its place we have Hawk-Eye, the creation of a relatively sane student of artificial intelligence from Durham University called Dr Paul Hawkins, who does not expect his computers to talk, but who has given tennis fans a whole new reason to go "Ooh" and "Aah".

Hawk-Eye is based on a triangulation system in which 11 cameras calibrate the position of the ball in 3D. The process is repeated for each frame so that the 3D position of the ball can be combined to produce a single trajectory of flight. Perhaps the most amazing thing about Hawk-Eye is that the device has been accepted by virtually every player with nary a McEnroe moment. Which, of course, has come as a relief to the present corps of umpires whose predecessors frequently found themselves having to endure verbal salvoes.

Only one player seems to hate it and, oh dear, his name is Roger Federer. "I don't see the point of it," says the man who some call the greatest player ever to pick up a racket. He has reduced the intrigue and excitement of this technological advancement to a throwaway line of chilling inconsequence. In doing so, he has revealed the sliver of petulance that lurks in his otherwise sunny nature.

In the heat of battle, Federer mocks Hawk-Eye. He treats it with disdain. And he does so by asking the umpire to bring it into use, as every player has the right to if he does not agree with a call, when the call has plainly been correct. "It's there," he has explained. "So I might as well use it. But don't ask me to like it." As a result, the great Federer has, on occasion, allowed Hawk-Eye to make him look silly, but if you carry as much talent in your kitbag as he does, you can afford to squander the odd point.

For the rest of the mortals on tour, Hawk-Eye is a way of settling disputes that might otherwise break concentration. I have never seen a player storm up to an umpire and scream, "Hawk-Eye is wrong!" They just get on with the next point.

Except on clay. The wonderful surface used at Roland Garros leaves a mark when the ball bounces, which is thought sufficient to decide queried calls. The umpire leaps down from his or her chair and points to the mark. "Out!" Or was it?

"We decided not to use Hawk-Eye on clay because it might not agree with the mark the umpire is pointing at," says Lars Graf, one of the ATP's most experienced officials. "Most clay courts now have embedded concrete lines that sit a millimetre above the surface. This means that a ball that nicks the line, and therefore is in, does not show up on the clay but would show up as 'in' on Hawk-Eye. That would cause a problem."